General structure and classification of hadrons with orientable strings and string junctions are discussed. In addition to the familiar meson M2 = qq̅ and baryon B3 = qqq, a lot of higher hadrons are expected to exist; linear tree family of M4, B5,…, and meson ring family of ~M2, ~M4,…. Even multibaryons and closed strings with junctions (but without urbaryons) are not necessarily ruled out. Mass, interactions, production and decay of orientable hadrons are examined. In particular, interaction rules are classified into allowed and forbidden ones, in conformity with the Okubo-Zweig-Iizuka and Freund-Waltz-Rosner selection rules for urbaryons and also with duality. The interaction rules forbid higher hadrons with three or more junctions to decay into two lowest hadrons (M2 or B3), and give possibilities to assign narrow NN̅ resonances at 1932 and 1897 MeV to M4, and ψ particles to ~M4 which should have a narrow width if its mass is lower than 4×(nucleon mass)≃3.76 GeV.